Elastic and non-elastic narrow fabrics / and a chapter on narrow fabrics made on knitting machines

by Samuel Brown

The Overshot Method

The overshot method, which we have previously referred to, is another form of double shuttle web which has in it elements of economy differing from the cross shot but equally important. This kind of weaving is designed as a substitute for silk jacquard webs, which it has to a great extent supplemented. Before its introduction it was customary to use a slow running “rise and fall” lay movement, when making a silk figure with the shuttle, putting in one pick of silk filling to each two body picks, so that the output of web was only about one-half of what is possible in overshot weaving. In the old method the silk used to pass from edge to edge of the goods at each pick of the figure shuttle, and where the figure did not appear it was buried between the upper and the lower cloths.

In the overshot method the silk figure is bound down at the edge or border of the figure and none of the silk is entirely buried out of sight. In the overshot the body shuttle runs all the time, while the figure or silk shuttle only runs with every alternate pick. The main body of the goods is woven in every respect the same as in a single shuttle web, and it may embrace all the weaves, such as plains, twills or fancies, which are common to single shuttle weaving. Arrangements are made, however, for the production of an auxiliary shed, by a movement which pulls certain threads above the main shed, and while these are open to pass the extra shuttle under them, and thus bind in the figure filling. The lower part of the lay has straight shuttles, while the upper bank of shuttles is tipped down to conform to the formation of the auxiliary shed they are designed to pass through.

The binder threads from which the overshot figure is generally operated, are weighted very lightly so that the individual threads will easily stand the strain they will be subject to while making the auxiliary shed. The Crompton & Knowles overshot dobby is generally used for this purpose. This special machine is provided with two horizontal draw knives, operating any or all of the 30 hooks, and is so arranged that the connected warp threads may be lifted at either or both picks to the height of the main shed, or to the additional height of the auxiliary shed.

Fig. 5.—Simple Overshot Design

Fig. 5A.—Draft for Fig. 5

In Fig. 5A is seen the draft of a simple overshot figure covering 23 hooks, which are operated from one knife drawing in unison with the binder harness, while the other knife is operating on the alternate shed, or the heavy pick, and working in unison with the rubber harness. It will be noticed that in the overshot design both sides of the figure do not operate alike, but follow one pick behind the other. This is so arranged that the binder may come up at the right pick to properly bind down the silk in the goods, and so avoid any irregularity or ragged appearance at the border of the figure.